Excel training guides/videos - https://support.microsoft.com/en-gb/office/excel-video-training-9bc05390-e94c-46af-a5b3-d7c22f6990bb
Basic tasks in excel - https://support.microsoft.com/en-gb/office/basic-tasks-in-excel-dc775dd1-fa52-430f-9c3c-d998d1735fca
Overview of formulas in Excel - https://support.microsoft.com/en-gb/office/overview-of-formulas-in-excel-ecfdc708-9162-49e8-b993-c311f47ca173