Hello-
The starred note on the piano is a C.
Some additional (and optional) information...
There are groupings of white and black keys - first three, then four, then three, then four... on and on across the keyboard. The starred key, C, marks the beginning of the group of three. That's how I know where to find C, and then by extension A, B, D, E, F, and G.
Hope this answers your question.