Hold the Option key and click the battery icon near the top of the screen.
You should see a "Condition" field that indicates whether your battery is performing as it should. If it says "Normal," your battery is operating normally, as Apple explains. But it could also say "Replace Soon," which would mean that the battery is holding less charge than when it was new and should be monitored regularly.
If this field says "Replace Now," it means that the battery is holding significantly less charge but is still safe to continue using. The "Service Battery" option indicates your battery isn't operating normally and should be taken to an Apple Store. You can still use it safely when connected to the right power adapter.
Click the Apple icon and choose "About This Mac" to see more information about your Mac's battery.
Choose "System Report."
You can also get to this step quicker by holding the Option key and clicking "System Information."
Click on the "Power" option to view details about your MacBook's battery.
From here, you can see information like your battery's cycle count, full charge, and charge remaining. A battery cycle occurs when your MacBook's battery has been completely depleted. If your MacBook has consumed all of its charge cycles, it's fine to continue using it but you'll likely notice a dip in battery life.