Meaning: This sentence is describing the girl consuming food in the middle of the day with the people who are liked and trusted.
Choice of Words: The word "girl" refers to a young female child. "Ate" is the past tense of "eat", which means to consume food. "Lunch" is a meal eaten in the middle of the day. "Friends" are people who are liked and trusted. When you put these words together, you get a sentence that describes a girl eating lunch with her friends.