Future Army Wife

After getting his associates degree my boyfriend is going to go to the army and he planned on like 4 years. I have an army family(not my dad or brothers but many cousins and uncles) but I don't really know what the army is. I know that sounds dumb I just don't know what he's going to be doing while he's in the army. Im really nervous about it and like I've been bringing up that we should get married and have at least one child before he leaves bit he said thats too soon for us. And that he didn't want me to raise our kids alone. Am I overthinking things? Like can someone explain it to me because all he said was basic training then he'd be stationed somewhere.