Mastering Categories in Numbers
What exactly are you trying to accomplish? Are you testing for the presence of the Groceries category label before adding the amount into your calculation? Are Category and Amount named collections/ranges?

The format for SUMIF is:

SUMIF(collection_to_test, "test condition", optional_collection_of_values_to_sum)


So assuming Category and Amount are named ranges, your formula should be:

=SUMIF(Category, "=Groceries", Amount)


If they are not named ranges, it would look like this:

=SUMIF(C2:C10, "=Groceries", D2:D10)


Naturally, substitute your own particular cell ranges for the first and last parameters.