Tables, or spreadsheets, are a semi-structured way of entering large amounts of data. If you are coming from Excel/LibreOffice, then you will notice that you can do a bit less than you might be used to. This is on purpose and helps you when you want to analyze it later. A good table follows these rules:
Like text sections, you can insert special types, such as counts, dates, times etc. The counting works a bit specially - If you use more than 1 counter, the values will be put in separate columns, moving from left to right starting at the current cell.