Vector Files - can these only be done on a Mac?

[Yankydoodledandy]

a friend has a jpeg and needs to convert the file into a vector file
Can this only be done on a mac???

No. It can be done on a PC too.
You'll need an appropriate program such as Adobe illustrator.
And you'll need to redraw (trace) it as a vector graphic otherwise you won't be able to enlage it without distortion/pixelation.
Someone more knowledgeable than me will hopefully be along to explain it a bit better.
What is it's intended use?

She's having something printed and they need a vector file she only has a jpeg

Cancel that just seen the file it's a psd file a photo shop type thing!!!

Is it a photo or something more like a logo/pattern etc?

looks like a pattern

@Yankydoodledandy

Cancel that just seen the file it's a psd file a photo shop type thing!!!

Almost sure you can use .PSD files in Gimp (free photo/image editor for PC/Mac) that will let you save as any file you want. PSD is a photoshop save file which retains all layers so you open and re edit each part individually without having to redo everything again.

I was going to have a go for her but as she's having something printed I think she needs to go to a pro and get it sorted as she will need it sharp

A vector file will be a .EPs or .ai.
A .PSD file might have paths you can use to recreate it as a vector.
The printer will probably want an .EPs .ai file or a rasterized (flat, no layers) file (Jpeg, gif) of a high enough resolution to print.
They should say what the minimum size (mm) and DPI it needs to be, and with your .PSD file, you should be able to save this to the correct requirements. (I may be wrong i've not dabbled in this area for years).

If you can't do it, someone on here might be able to save it at the right size for you. Just say it needs to be ie; 100mm X 200mm @ 300dpi and a gif/EPs....or whatever.