When you work continuously in Microsoft office tools, it is better or easy if you can repeat the previous action / task in the spread sheet or document. Here are some examples like bold the different columns delete some rows or columns from the spread sheet,
highlight or make different rows or columns etc.
There are two different short cut keys provided by Microsoft office.
1. Press F4 key to repeat the previous or last task
2. Press CTRL + Y to rerun the last task.