If the EFC in question is the one that the school uses, then your “need” as the school defines it is $25k. If the school “meets need” then it will offer $25k in financial aid, although it may assume that you will take subsidized federal direct loans and earn some money from part time work earnings (subsidized by work-study) for some of that (usually up to $5k to $10k, so grants would be $15k to $20k in this example).
Of course, most colleges do not “meet need”, so if such a college determines that you have $25k “need”, its financial aid offer may still be less than $25k. For example, it may assume $3k loan, $3k work-study, and $10k grant, leaving unmet need of $9k.
If you earn a merit scholarship, school policy varies on how it will affect your aid. It may depend on whether it is a school awarded scholarship or outside scholarship, and different school awarded scholarships may have different policies. It is common, but not universal, for outside scholarships to replace unmet need, student loan, and work study first, then replace school grants (limited “stacking”).