The maximum allowable HSA contribution depends on a few things- whether you had an individual or family plan ($4,150 and $8,300, respectively), your age (and additional $1,000 is allowed if you're 55 or older), and whether you had a high deductible plan the whole year or for only some months in the year. When you and your employer's contributions exceed the maximum, you have overfunded your HSA.
Here's an article you may find helpful: Why am I showing an excess HSA contribution?