Yeah, so many people try to breathe out when their head is out of the water - it makes it much more tiring and slows you down as your timing goes out of whack and your legs inevitably drop.
When I say ‘stay long’ I mean that you should aim to be as flat and narrow in the water as possible. Reach out with your arms and stretch your legs out and keep that feeling in your head. For front crawl your legs should be long and bend from the hips, not the knees, and your hand should enter the water inside of your shoulder line, with your body rotating slightly to extend your reach, and then hold it there, until your other arm is passing your head on the way back.
A lot of people don’t reach out with their arm and bend from the knees, which makes their legs drop in the water. It should be a long, relaxed stroke, not a windmilling splash.