Step two of logging a strength set: confirm how many reps you actually got.
The number starts on the set's target rep count, not blank — most sets just need a tap of START if you hit the target exactly.

There's no "wrong" number to enter here — the target is a starting point, not a requirement. Whatever you log, even below the target, is what the app coaches from next time; see "Why didn't my target go up this session?" for how that works.
Related: "The weight screen on your watch", "What is RIR (reps in reserve)?", "Why didn't my target go up this session?".