With” is a preposition that can be combined with nouns and modifiers to form prepositional phrases. It has a few meanings, including the following:
Who an action is performed with: “I went to the cinema with my brother.”
A combination of items: “they served tea with milk.”
What is used to carry out an action: “I wrote the letter with a fountain pen.”
How something is done: “They danced with skill and grace.