one step; a single step
Refers to one footstep or the act of stepping once. In ordinary counting of steps, 一歩 is more common, while 一足 often has a slightly written or set-phrase feel.
He moved along the snowy road, checking each step carefully.
short distance; a little way
Used for a small physical distance, often with expressions like ほんの一足 or あと一足. It can sound more idiomatic or literary than simply saying 少し.
The sea is only a short distance from the inn.
a short time; a little earlier or later
Common in fixed expressions about a small difference in timing, such as 一足先に, 一足遅く, and 一足違い.
I'll excuse myself a little ahead of you.
I missed the train by just a moment.
We're just one step away from reaching the summit.
The station is just a short walk away.
I arrived just a bit after him.
He jumped straight to department manager, skipping the usual ranks.