Unbilled Charges is the amount on top of your Monthly Service Fee (MSF). It may not reflect charges from the last 2 hours and does not include amount of Share-a-Load transferred, Value-added services charges, and call/text/surfing promo registration fees. Your plan's allocation and freebies will be consumed first before you are charged with the applicable rates.
By the way, you can check your Postpaid Outstanding Balance and other account details via MyAccount. Just register or login at http://accounts.globe.com.ph If you're always on-the-go, you can download GServices app from the Google Play Store (Android devices) and Apple App Store (iOS devices).