A person who begs asks for something. This is a popular word to use when something is desperately needed.
The man got down on one knee and begged the woman to marry him. (It’s hard to hear the "ed" ending; however, the first verb in this sentence, "got," reinforces the use of the past tense for the second verb, "begged.")
The little girl begged her mother for some candy.
The students begged the teacher for more time to finish the assignment.
The driver begged the police officer not to give him a ticket for speeding.
TV commercials beg for your attention.
Dogs beg for food whenever possible.
If you visit any big city in the United States, you’ll see people begging for money.
A person who begs for money is a "beggar."
Note: Instead of using the word "beggar" to describe someone begging for money, Americans often use the term "homeless person" because people who are homeless and living in the streets are usually the ones who beg. So you would say something like, "We saw a lot of homeless people begging and living on the street."