The word babe has two main meanings:

1. A baby or very young child. Parents might call their infant a babe in arms, meaning a child too young to walk and still carried everywhere. You'll find this usage in older books and traditional phrases, like “babes and children” or the Christmas carol line about the “little Lord Jesus, no crying he makes.” While people don't use babe for babies as commonly today as they once did, you'll still encounter it in stories, poems, and songs.
2. An informal, affectionate term that people use for someone they care about romantically. A husband might call his wife babe, or vice versa. It's similar to other affectionate nicknames like “sweetie” or “honey.” You hear this usage frequently in everyday conversation between couples.

The word can also appear in the expression babe in the woods, meaning someone innocent and inexperienced who doesn't realize they're in over their head. A sixth-grader trying to understand high school algebra might feel like a babe in the woods, lost and confused by something beyond their current knowledge.