You have several options;
Soft reset,
press "Power" and "Volume Down" button simultaneously for 12 seconds. You'll see the "Maintenance Boot Mode" screen. Use "Volume Down" button to navigate to "Power Down" option and press "Power" key to confirm your choice.
Safe Mode;
Step 1. To enter the safe mode, power off the device, then press and hold the "Power" button until the logo screen appears. Release "Power" button and keep holding "Volume Down" button until the phone reboots with "Safe mode" on the lower left of the screen.
Step 2. Go to "Settings" > "Apps" and select the downloaded apps. Then uninstall the apps that are newly installed or you are unfamiliar with. After that, you can restart the phone and exit safe mode.
Recovery Mode;
Put your Samsung device in recovery mode. Power off device then/or "Power" + "Volume Up" and "Home" button at the same time until the "recovery mode" menu appears.
Then use Volume up/down buttons to navigate menu and choose clear cache, Then reboot phone.