Burning your brides

does anyone know what "burning your bridges" means since I have heard it in quite a few songs and don't understand it.

"Don't burn your bridges behind you" is good literal advice for an army. If they have to retreat, they could be trapped, unable to move from a riverbank.
It's also good advice for the rest of us in a metaphorical sense. Don't tell off the boss on your last day of work, for example. Someday you might -might - need to work there again, or he may show up to replace your new boss at the next job six months from now. Always leave people on good terms - you never know when you may meet them again.

Did somebody mention burning brides?

Back on topic - if a commander wanted to make sure that an army could only advance, they would sometimes burn the bridges they had passed - but it means that there is a nightmare of a logistics problem trying to re-supply the force, so it tends to mean a dramatic gesture done for effect that has the consequence of both preventing you going back and causing other problems.