"The Battlecruiser is highly specialized in the interception of hostile fleets."

How do i intercept ships????

intercepting, meaning it is faster than most war ships and can head them off at the point of attack, i.e. your planet A is being attacked. They are using DD's and BS and a combo of others for example. The Battlecruisers are fast and can get to the point of contact to help defend and defeat the oncoming attack. The biggest problem at the current moment is that BC's rely heavily on RF against other ships. Since that feature is not implemented yet.. the BC's are less favorable to use as they have less firepower than BS or DD

It just a description, it doesn't mean you "intercept" ships in the game. There are other ways to time an attack and catch someone's fleet on it's way back to their planet/moon with any kind of ships.

yeah, i answered the question with relation to Battle Cruisers only, which is what he related his question to.