To Join Together
To Unify, To Match
transitive verb, ichidan verb
You know that the alternative kanji meaning for 合 is join, which is what we're using here. The verb form of join is to join together, and it can also mean to unify and to match.
The reading comes from 合う, so if you know that reading you'll know this reading as well.
顔を合わせる
to meet face to face
手を合わせる
to join one's hands together
力を合わせる
to join forces
都合に合わせる
to suit one's convenience, to accommodate someone's schedule
ニーズに合わせる
to adapt to the needs of
人に合わせる
to adapt oneself to suit others, to have someone meet someone
彼は相手のペースに合わせるのが上手いよね。
He's good at matching the pace of others, isn't he?
このセーターに合わせる上着がない。
I don't have a jacket that goes with this sweater.
ムリして人に合わせる必要はないよ。
You don't need to force yourself to fit in with others.