Will I be charged for sharing my internet connection via the personal hotspot on my iPhone?

If I wanted to let someone use the Wi-Fi by turning on the personal hotspot on my phone will I be charged?

If you don't have a tethering plan, then you may be charged, or it might not let you activate it.
It's best to contact your carrier for a more accurate answer. No, only your data will be used and you should also get LEO Privacy Guard 3.0, so as to secure all of your device totally.

No, only your data will be used and you should also get LEO Privacy Guard 3.0, so as to secure all of your device totally.