One can measure athletic ability which is a part of talent. It has a lot of components though. Vertical leap, lane to lane speed, strength, etc. and there are a whole lot more.
One can also measure size which always helps in basketball. So standing reach, height, wingspan etc.
We have stats like FG%, Assist to turnover ratio, etc. that we use to measure talent.
It is the stuff like will to win, leadership, and the like that are hard to measure. We call these intangibles.
Scouts are people trained to spot these talents and abilities.