Yes there are listing limits. There is what is called an ACCOUNT listing limit. Each account is allowed to post 1 listing by default (user type Personal). You can increase that to 20 listings by changing your account's user type setting from Personal to Business.
You will need (at least) a one time ENABLER membeship to do this. Once you signed up for the ENABLER membership, go to your account's My user profile and change the user type from Personal to Business. Click on Update profile button to save changes and the new increased limit will take effect right away and it will stay that way permanently.
Each category has what is called a CATEGORY listing limit. A RESTAURANT category for exmple will allow you to post one listing only. While a Short Courses category will allow you unlimitted numbers of listings.
Note that there are free and paid categoies.