@ro14,
Do a search for "asymptotic limit" instead: if you only search for "limit" you're unlikely to find the mathematical meaning.
Here's an example of an asymptotic limit (blue line) you want to approximate by using small straight lines, or steps. As you make steps smaller and smaller (red function) the red line comes closer and closer to the blue line (its asymptotic limit) but never quite overlaps with it completely until and unless you use an infinite number of steps:
This is a specific function (for harmonic numbers) but if you search for asymptotic limit images you'll find lots more.