Soldier
Sailor
noun
A soldier in a squad is a real soldier or sailor, unlike those "soldier" who are not in a squad. They don't have jobs, and can't be called real soldiers.
へいたい
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
兵隊ごっこをしているの？面白そう。私も入れてよ。
Are you guys playing soldiers? That looks fun. Let me in too.