You Do Need power plug adapter while traveling from Yemen to Poland.

Here is Why You Need An Adapter

The outlet and plug type used in Poland are C and E and in Yemen are A, D and G. This is how they look like.

Yemen

In Yemen, outlets of type A, D and G are in use.

Type A

Type D

Type G

Poland

In Poland, outlets of type C and E are in use.

Type C

Type E