My reply might also help your own pursuits as a model.
A tear sheet is physical prove of a modeling job in the form of a catalog, magazine, or print ad. The "tear" part means that you physically tear the resulting image out of the magazine or catalog.
Then the tearsheet goes from the catalog or magazine page to now inside your portfolio, so you are actually ripping it out of the magazine, catalog, etc.
Of course in this Internet age there could be an online catalog or online ad or editorial as well, and I suggest all models have some basic computer skills for knowing how to "print screen" and then paste the image in Photoshop and make the image print size- which is 300 dpi, or by using the a the Windows Paint program paste the "print screen" image and adjust the sizing there. Your goal as a model is not just to be booking modeling work but to make sure you have the credit of your work.
So that you can put credible tearsheetst/credit on your compcard, or in your portfolio.
A tearhsheet is prove of the modeling job you did for a magazine editorial, marketing campaign, or catalog. Having tearsheets is important because it proves you are working with brands, magazines, and doing professional work and by having tearsheets it can lead to more credible work.
Here is more insight below on getting tear sheets, collecting your tear sheets and why they are important for aspiring model to gain.
Be on the look out for credit of your work because you need that tear sheet in your portfolio!:
More tips for collecting your work:
Why tear sheets matter for models:
(this is from the Easy Spirit print catalog and I scanned in my scanner but the print edition is in my portfolio and when I made a comp card I brought the print edition to the comp card printing studio for them to scan and use on my card.)
(from the Easy Spirit website)
(Since I couldn't take this poster home, I just took a photo, but I won't put this on my comp card, I would add it to my website, or send a jpeg of it to my agency to they could have it on file to show future clients perhaps, but the actual tearsheet from a catalog, online ad, product print is better to put on comp card or in portfolio. Like below)