The night prayers are two by two, and Witr is one rakah at the end of the night Sahih Muslim 749 b
Translation
Salim reported on the authority of his father that a person asked the Messenger of Allah (ﷺ) about the night prayer. He said
It consists of pairs of rak'ahs, but if one fears morning is near, he should make it an odd number by praying one rak'ah.