How do bond ETFs pay you?

I have uninvested cash that I’m considering placing in a bond ETF like SGOV. However it seems the price of the ETF can go up or down drastically - does this mean you’re are putting your principle investment at risk?

I also don’t understand how the yearly interest (e.g. 5% yield) is paid to you. Is it considered as capital gains, or dividends, as there are different tax implications for each. And are these automatically reinvested into the ETF?

I couldn’t find much info about this, thanks for the help!