Why does c# have [ ]?

Why does c# have [ ]? Below is an example of code that currently has me confused. I’m new to C# and i want to understand the language.

public class ExternalLoginConfirmationViewModel
{
    [Required]
    [Display(Name = "Email")]
    public string Email { get; set; }
}

What I’m wanting to understand is how the code processes the parts of code like

[Display(Name = "Email")] 

Thanks in advance