✅ I need help with explanation of given entity attributes

        [Timestamp]
        public byte[] RowVersion { get; set; }
        public DateTime CreatedAtUtc { get; set; }
        public DateTime ModifiedAtUtc { get; set; }

[Index(nameof(UserName), IsUnique = true)]
[Index(nameof(Email), IsUnique = true)]
public class UserEntity
{

    [Timestamp]
    public byte[] RowVersion { get; set; }
    public DateTime CreatedAtUtc { get; set; }
    public DateTime ModifiedAtUtc { get; set; }

    [Key] public int Id { get; set; }

    [Required, MaxLength(30)]
    [RegularExpression ("^[a-zA-Z0-9]+$")]                                                              //User name should not contain special characters
    public string UserName { get; set; } = default!;

    [Required, MaxLength(254), EmailAddress]
    public string Email { get; set; } = default!;

    ... More  attribut...