Hello
I have got macros "embedded(?)" in my excel spreadsheet and when i open it, it says

"Macros in this workbook are disabled because the security level is high, and the macros have not been digitally signed or verified as safe. To run the macros, you can either have them signed or change your security level. Click help for more information"

what is a ddigitally signed macro and how can i digitally sign a macro

also how can i reduce the security level of my excel spreadsheet?