Software for generating invoices

Hi there.

I am a small trader.
Sometimes my clients ask me to send invoices in google docs, sheets, pdf, etc. That’s why I was seeking for software for creating invoices in different formats.
I managed to find a site with templates and I’d like to ask experienced users what exactly should I put in the following fields: business and client’s details.

Thanks in advance for your help.

[i]Link to site with templates removed by moderator. Not necessary for the question.[/i]