才能 has two distinct uses depending on context. As a noun it means talent or ability - an innate or acquired skill (有才能, to have talent). As a verb phrase it means only then can or only by doing X can one Y - here 才 acts as an adverb meaning only then and 能 means can. The two uses are distinguished by whether 才能 is followed by a noun (talent) or a verb (only then can). Both uses appear very frequently in Mandarin.