The phrase "several tabs" refers to having multiple internet browser windows or pages open at the same time on a computer or mobile device. Full definition
This feature will be great for students, who may find themselves doing research for a report, with several tabs open at one time. (windowscentral.com)
My «system» probably deserves a post to itself, but basically I have a spreadsheet with several tabs that I used to track spending, card login info, bonuses, etc.. (pointswithacrew.com)
There are several tabs containing information specific to a case number / property. (iloanhomemortgage.com)