で遊んでます

are playing with

→ で
phrase Rare #39,468
are playing with The particle で marks the place or thing used for playing. 遊んでます is the polite conversational form of 遊んでいます, meaning “am playing” or “are playing” depending on the subject.
JA: 友達と公園で遊んでます。
EN: I'm playing at the park with my friends.

パソコンで遊んでます

I'm playing on my computer.

妹はで遊んでます

My younger brother and sister are playing in the garden.

男の子たちはまだ砂場で遊んでます

The boys are still playing in the sandbox.

子供たちはまだ砂場で遊んでます

The children are still playing in the sandbox.