His exact question was, "How can I freeze a worksheet both horizontally and vertically at the same time? "
Technically, he meant how can I freeze row(s) and column(s) simultaneously in Excel.
It is a common question that people also ask during our training sessions. I have a very interesting way of explaining it such that you can't get it wrong but I am unable do that via an article. It's a mix of captivating stories and live demonstration.
However, I'll give you a summary answer that will guide you if you have such problem in Excel. It is very easy to implement and remember too.
You click on the cell below the row you want to freeze and after the column you want to freeze. Then you click on View menu, Freeze Panes, Freeze Panes.
Below is an illustration of how to freeze row 1 and column 1 at the same time. It can be applied to any number of rows and any number of columns.