Method 1:

\dp <schemaname.tablename>

Method 2: 

using information_schema.role_table_grants.

View "information_schema.role_table_grants"

Column |           Type            | Modifiers

---------------- +----------------------------------- +-----------

grantor    | information_schema.sql_identifier |

 grantee    | information_schema.sql_identifier |

 table_catalog  | information_schema.sql_identifier |

 table_schema   | information_schema.sql_identifier |

 table_name | information_schema.sql_identifier |

 privilege_type | information_schema.character_data |

 is_grantable   | information_schema.yes_or_no  |

 with_hierarchy | information_schema.yes_or_no  |

There are few information schema views which can be used to see grants.

gpadmin=# \d information_schema.*gran*

View "information_schema.role_column_grants"

 Column |           Type            | Modifiers

---------------- +----------------------------------- +-----------

grantor        | information_schema.sql_identifier |

 grantee    | information_schema.sql_identifier |

 table_catalog  | information_schema.sql_identifier |

 table_schema   | information_schema.sql_identifier |

 table_name | information_schema.sql_identifier |

 column_name | information_schema.sql_identifier |

 privilege_type | information_schema.character_data |

 is_grantable   | information_schema.yes_or_no  |

View "information_schema.role_routine_grants"

Column  |          Type            | Modifiers

------------------ +----------------------------------- +-----------

grantor      | information_schema.sql_identifier |

 grantee      | information_schema.sql_identifier |

 specific_catalog | information_schema.sql_identifier |

 specific_schema  | information_schema.sql_identifier |

 specific_name | information_schema.sql_identifier |

 routine_catalog  | information_schema.sql_identifier |

 routine_schema   | information_schema.sql_identifier |

 routine_name | information_schema.sql_identifier |

 privilege_type   | information_schema.character_data |

 is_grantable | information_schema.yes_or_no  |

View "information_schema.role_udt_grants"

Column |           Type            | Modifiers

---------------- +----------------------------------- +-----------

grantor    | information_schema.sql_identifier |

 grantee    | information_schema.sql_identifier |

 udt_catalog | information_schema.sql_identifier |

 udt_schema | information_schema.sql_identifier |

 udt_name   | information_schema.sql_identifier |

 privilege_type | information_schema.character_data |

 is_grantable   | information_schema.yes_or_no  |

View "information_schema.role_usage_grants"

Column |           Type            | Modifiers

---------------- +----------------------------------- +-----------

grantor    | information_schema.sql_identifier |

 grantee    | information_schema.sql_identifier |

 object_catalog | information_schema.sql_identifier |

 object_schema  | information_schema.sql_identifier |

 object_name | information_schema.sql_identifier |

 object_type | information_schema.character_data |

 privilege_type | information_schema.character_data |

 is_grantable   | information_schema.yes_or_no  |

Method 3:

SELECT nspname, relname, relkind, unnest(relacl) relacl FROM pg_class AS c, pg_namespace AS n WHERE n.oid=c.relnamespace AND n.nspname=schema_name AND relname in (list tables) ;

SELECT nspname, relname, relkind, relacl FROM pg_class AS c, pg_namespace AS n WHERE n.oid=c.relnamespace AND n.nspname='schemaname' AND relname =’tablename’ ;

SELECT nspname, relname, relkind, rolname AS rel_owner, unnest(relacl) AS rel_acl

FROM pg_class AS c

LEFT OUTER JOIN pg_namespace AS n ON n.oid=c.relnamespace

LEFT OUTER JOIN pg_roles r ON r.oid=c.relowner

WHERE n.nspname='schemaname'

AND relname =’table_name’

SELECT has_schema_privilege('username', 'schemaname', 'USAGE') ;

SELECT has_table_privilege('username', ‘schemaname.tablename’, 'SELECT') ;

Method 4:

select

          t.grantor ,

          t.grantee,

          t.table_schema,

           t.table_name ,         

           array_to_string(array_agg(privilege_type::varchar order by privilege_type),',') as privileges

        from information_schema.table_privileges t

        left outer join pg_catalog.pg_partitions p

          on t.table_schema = partitionschemaname

         and t.table_name = partitiontablename

        where rtrim(t.table_schema) like lower('%')

         and p.partitiontablename is null

         and privilege_type != 'TRUNCATE'

         and t.table_schema = 'schemaname'

        group by 1

        order by 1;