The term bandwidth limit exceeded means the quantity of bandwidth that was allotted to the hosting set up has been reached. bandwidth is consumed once knowledge is retrieved from the server and delivered to the top user (outbound traffic) furthermore as once the top user uploads information to the online server (inbound traffic).
Everything you do (posting, voting, commenting, etc.) will consume a small amount of bandwidth. Every user has a limited amount of bandwidth to use each week. Users with more Steem Power will have a higher bandwidth allowance.
Normally everyone's bandwidth allowance is quite high, and users are able to use the network freely without any interuptions.
Sometimes when the blockchain becomes very busy (due to heavy use), the bandwidth limits for all users will be lowered. This will primarly affect users with a small amount of Steem Power.
If you get an error that you have exceeded your bandwidth allowance, it is normally best to just wait (an hour or two) and try again when it is less busy.
If you want to increase your bandwidth allowance, you can purchase more Steem Power for your account through an exchange such as BlockTrades.us.