The Prague Post is one way of getting news in English – and widening your English vocabulary.
I found it hard to follow the week’s big political news in Czech so I had a look at the Prague Post today: Convicted Bárta vows to stay in politics.
If you vow to do something, it’s a serious promise you make publicly or to yourself. It’s often used in newspaper headlines. Another example:
Obama vows to complete Afghan mission [from the Financial Times]
Usually the person who makes the vow is facing a big challenge and vows to do something to solve the problem at hand.
As a noun, vow can also be used when people promise to be with each other in marriage. They exchange vows (or marriage vows).