There are two main types of table in Excel: the formal and the informal.
Formal tables are part of the Excel “toolkit”. To add one, go to the Insert tab, and Table can be found in the Tables group.
Both types of tables are well organized data in columns, together with any calculations or functions would help with usage or analysis.
Structuring data well is the most important thing that can be done in Excel (or any system) because it makes manipulation and analysis much more powerful.
Once you have your table, you can also apply Autofilter, which provides a powerful manipulation and analysis tool without any need for knowledge or application of formulae. (and if you can do those, then Autofilter is even more powerful).
Formal tables have Autofilter added automatically, together with other table functions, but these can be confusing, so you may prefer a simple table.
Formal tables automatically expand (together with any formulae) as you add extra rows, which is very useful and also reduces the problem of the actual table not being as big as it looks.
There can be more than one formal table per spreadsheet, whereas informal ones are restricted to one per sheet.
Please note: “formal” and “informal” are terms I have used to differentiate the two types. They are not official terms.