Yes, the STM32F7 has an RTC. Check out the datasheet [here](https://www.st.com/resource/en/application_note/dm00226326.pdf) for the details.
TL:DR; The RTC provides date/time keeping, along with features for setting alarms, and a few other things. In many designs, the RTC is backed up via a coin cell battery so if the main power supply is cut, then date/time is kept on the chip. In the meadow design, we've replaced this functionality with the main battery input. Meaning if you need to keep the date/time during a main power loss, you can just make sure there's a LiPo/LiIon battery plugged in to the battery in connector. Even better; since there's a built in charging circuit, you can rest assured that the battery is always topped off, as long as you have main power to the board via the USB or the VIN pin.
Additionally, even if you lose all power and have no battery back up, as long as you have connectivity, you're covered because you can always do a call to a time server on the internet to get the current date/time. In fact, we plan on building this functionality directly into the Meadow OS so that it can do that for you automatically.
Also... The RTC will keep time even when Meadow is in a deep MCU sleep. :)