Rule 411 Except where additional evidence is required by statute, the direct evidence of one witness who is entitled to full credit is sufficient for proof of …

One witness can be enough to prove a fact in court. You do not need multiple people to say the same thing for a judge or jury to believe it.

There are some exceptions where the law requires more than one witness or extra proof, but those are specific situations spelled out elsewhere. In most cases, if one believable witness testifies about something they saw or heard, that testimony alone can win the point.