Need explanation on how this macro works

I have a macro that was writen a while back by a coworker that I need help understanding. I have attached a picture of the spreadsheet columns in question. The macro starts by looking in column 46 (AT) for the number 1 and then at some point changes the 1 to a 0. That's as much as I understand.

Could someone please describe in detail what is happening in this macro, step by step. What the s and v and e are meant to do. If I understood this macro then I could possibly reproduce it in another file, which I'm hoping to do.

Sheets("datastrings").Select
s = 1
    Do Until v = 1
        v = Cells(s, 46)
        s = s + 1
    Loop
    
e = s
    Do Until v = 0
        v = Cells(e, 46)
        e = e + 1
    Loop