Translation of "Serte" in English

Toma este paraguas plegable contigo. Podría serte útil.

Take this folding umbrella with you. It might come in handy.

A mí, para serte franca, me parecía feísimo lo que esos chicos estaban escuchando, pero a ellos les parecía hermoso.

If I'm being honest with you, the music those kids were listening to seemed awful to me, but to them it was beautiful.