is possible to add time related values to excel?

Hi Alba, Thank you for your post, welcome to the forum, in response to your question, I am not 100% sure what you mean, you can use time in Excel because time is expressed as a value, if you wish to have the time displayed in a cell you should enter hours:minutes:seconds separated by the full colon (:) example 12:15:30 Excel will recognise that this is to be a time value, and will enter it in the cell accordingly, if you change the value to a number (General) Excel will display it as a decimal part of a full day (1) so therefore noon will be 0.50
Once you have entered this value as a time, you can calculate the total, between 2 or more cells, you can find the difference, add minutes and even seconds to the values, if your sum is greater than one day you will be given the value for the time in the following day, it will run sequentially, eg 12:00 + 12:15 will give the answer 0:15. I hope that has answered your question, best regards Pete