regression is a model that uses inferential tools. when SPSS estimate the coefficients of the regression (what is called beta's in SPSS) it is doing hypothesis testing, which is inferential.

you start with a sample, you calculate the coefficients, and then you can take values from the population, call them X1 and X2, and you can predict the value of Y knowing these values. but be ware, you can only make predictions in the range you had in the sample.