Disclaimer: Database maintenance tasks are outside of the scope of support. The following information is provided as-is and not warrantied.

What does this mean?

You database consists of two files - a data file and a log file. The log file is used by SQL Server to track data as it is changed. This allows it to recover in the case there is a problem. This can be a useful feature. but if not properly maintained, your log file can continue to grow and grow, tracking each data change until it is larger than the database itself. 

Why is this important?

Large log files can cause several problems. Most obviously, it can waste large amounts of space on a hard drive. Larger log files will slow down transaction processing and are also more likely to get corrupted.

How are problems identified?

The DB Health check reads the size of both the data and log files. There is no absolute limit for how large a log file should be, but if the log file is multiple times the size of the data file, we consider this a sign of poor log file maintenance. If the log file grows to 5 or 10 times the size of the database, we consider this a major problem.

How do I fix this?

The best way to keep the log file small is though a regular backup plan. When a database backup is created, typically this will remove the log data and shrink it down to a small starting size. Consult an IT professional for more information on setting up a database backup or addressing other transaction log problems.