What causes High VLFs?
As transactions force growth of the log file, inappropriate log file sizing or auto-growth settings can cause a high number of VLFs to occur. Each growth event adds VLFs to the log file. The more often you grow in conjunction with smaller growth segments, the more VLFs your transaction log will have.
If you grow your log by the default 1 MB you may end up with thousands of VLFs as opposed to growing by 1GB increments. MSDN does a great job on explaining how a transaction logs work for a deeper dive I recommend reading it.
Read on to see how many VLFs your databases have, as well as how to reduce the number should it grow excessive.