most; best
「一」 has other readings with different meanings.
one; 1
one
彼はクラスで一番背が高い。
He is the tallest in the class.
一の腕前を持つ職人に頼んだ。
I asked a craftsman with the best skills.
この店のラーメンは町で一美味しいと評判だ。
This shop's ramen has a reputation for being the best in town.