The device info page will provide details regarding the health of the battery for the device. Below is an explanation to help you better understand what the data provided means.
iOS
Battery Cycles: Counts how many times the device has been charged to its full capacity. This can mean either being charged from 0%-100% in one charging session, or being charged from 50%-100% twice on two separate charging session.
Battery Health: Is a measure of the current condition of the battery.
Build Battery Capacity: Shows the capacity of the battery when the device was manufactured, measured in milliamp hours (mAh)
Current Battery Capacity: Shows what the current capacity of the battery now is compared to when it was manufactured. Over time due to degradation of the chemical components from repeated charging and the passage of time, the capacity of the battery will degrade. A standard iPhone battery is built to retain 80% of its original charge capacity at 500 charging cycles.
Overall Battery: Combines each of the metrics (e.g cycle count, battery health) to produce a rating of the overall battery state.
Battery Health Flag: Is a measure of the current condition of the battery using a traffic light system
Android
Battery Temperature: Reports the current battery temperature as reported by the internal sensor within the device.
Battery Level: Displays the current battery charge level of the device.
Battery Health: Is a measure of the current condition of the battery.