Step 1. Check if Location Services are on, and Safari (or any other browser you are using) is allowed to use them (Go to Settings > Privacy > Location Services). Make sure "Precise Location" is also enabled.
Step 2. Verify that Safari grants location access on all websites or at least asks for permission (Go to Settings > Safari > Location). Select either 'Ask' or 'Allow'.
Step 3. If all the above fails, you can also try resetting 'Location and Privacy' in the General menu section (Go to Settings > General > Reset)
If your device uses stock Android please visit Android Help Centre for detailed instructions on how to manage Location Accuracy.
If you are using an Android/MIUI device (e.g. Xiaomi):