Can someone give me an easy explanation about bonds and SVB incident?

I know that bonds are kind of certificates paper that the organization/government lend it to you, so that you loan them money (price of the bond), that bond has a face value, and when it is mature, the investor will sell back the bond, and gain money based on the bond interest rate

Now, I read somewhere on this subreddit, that when FED increased interest rates, it suggested the SVB to sell the bonds, however.i don't understand how increasing interest rates is damaging to the bonds that the bank got from the FED/government 10 years ago?

I am aware there is like different type of bonds, but I don't know the details

An ELI5 explanation would be great