If it was Monday yesterday, then the day tomorrow will be Tuesday. This is because the days of the week follow a predictable pattern, with Monday coming after Sunday and Tuesday coming after Monday.
If you know the day of the week for a particular date, you can easily determine the day of the week for the next day by moving forward one day in the week.
For example, if you know that a particular date is a Tuesday, then the next day will be a Wednesday, and the day after that will be a Thursday. The days of the week will continue to follow this pattern, with each day coming after the previous day in the week.