Ticking noise is coming from front right under the hood

Near the headlight from a small piece that's connected near these aluminum tubes It's a small plastic square block w two wires coming out the top that plugs straight down into its place. Im not sure what it is or what its function is. However, it makes a consistent ticking sound at all times while the motor is on.

You can feel a tapping/knocking feeling when touching this piece. Can you explain to me what this part is, its function, the cause of it clicking and if this is a major or minor problem and if replacing it is costly? Also how to replace it if it is faulty. Thank you very much!!!