You can choose among a few different speeds, and the app will show you how long the hyperlapsed video will be for every speed in comparison to the length of the video in real time. (So a 40-second video in real time will become roughly a seven-second video in Hyperlapse at 6X speed.) It's a really cool way to capture something that usually lasts a while -- like a sunset or an event setup.
The T#i line is what they call a "pro-sumer" line, which is basically between a consumer line camera like a very basic DSLR and a professional DSLR camera, thus the term "pro-sumer." Typically what this meant is an DSLR with an APS-C sized sensor, decent resolution, and some hand-me-down professional features of pro-grade cameras from a few years ago. For this reason, sometimes it's not worth upgrading from one of these cameras to the next until at least a few generations have past (meaning if you have a T5i, it's not really a giant leap forward to upgrade to a T6i). However, the T7i is somewhat different. When I was doing research on what features it has and what it is missing compared to the pro-grade DSLRs that are considered "current" right now, I was surprised to find very little. The main differences really is that the pro-grade cameras have the LCD display on the top that would display all of your relevant camera settings, and then a few of them would also sport a full-frame sensor. Other than that, the differences are very minor. Something like maybe 1 or 2 frames less in burst mode or something like that. Nothing that would really jump out at you and make you regret not stepping up to the professional grade equivalent (Think it would be the 77D?). It actually has pretty much all of the big features of even their current pro-grade DSLRs, making the T7i probably one of the best prosumer DSLRs to buy.