Assuming you are asking about a credit score in the United States, the following applies.
To find out your FICO score, navigate to AnnualCreditReport, the official site to help consumers receive their credit report from each of the three organizations providing these scores - Equifax, Experian, and TransUnion. You are - in many states - entitled to a free copy of your credit report from each of these organizations annually.
This copy of your credit report will not contain your credit score from that organization. It will, however, contain information that goes into your credit score - the lines of credits on file, any delinquencies reported, etc.
If you decide you would like to pay for your credit score from each bureau, you will have the option to receive this information while getting your credit report, but you will have to pay a nominal fee for it. Remember that each of the 3 bureaus gives you a different score. Averaging your 3 scores should give you a good idea of your FICO score. Note that your report is far more important than your score - once you know that, you know if you're in a good place or not.
These other questions are so close that they might even be considered duplicates, and provide other suggestions for how to check your score.
As a warning, don't trust the many ads out there saying you can get your score for free. Only AnnualCreditReport is considered a safe place for entering the very personal information required to get a score. The FTC backs this up.