People talk about "the key length" in discussions of the RSA algorithm.

In learning about it at a textbook level I know that an RSA key is a
pair of integers. (One is used as a power to exponentiate a value and
ususally labeled e or d, the other as a divisor to then divide the
result usually labeled n.)

So what does "the key length," as a singular reference, refer to?? For
example if I hear about a "1024-bit RSA key" what is 1024 bits long?