A turn to the left; making a left-hand turn—used for directions and traffic (noun; can be used with suru as a verb).
次の交差点を左折してください。
Please turn left at the next intersection.
ここは右折禁止、左折のみ可能だ。
Right turns are prohibited here; only left turns are allowed.
左折するとコンビニが見えます。
If you turn left you'll see the convenience store.