When your photographer hasn't set a package
The bar at the bottom simply shows Selected X of Y photos, meaning how many you've selected out of all available photos. How many you can choose depends only on your agreement with your photographer.
When a package is set
The counter changes to Selected 7 / 5 in package, and the extra photos are highlighted as +2 extra. That means two photos go beyond the agreed number. The bar in the card at the top of the gallery shows the same thing: 7 of 5 in package and +2 over package, or, before you go over, something like 3 left.

How much an extra photo costs
The price isn't shown next to the counter. You'll find it in one of three places:
- from your photographer, by email or in a conversation before the shoot,
- in the expandable Pricing section in the card at the top of the gallery, if your photographer attached a price list,
- on the payment page, after you click Confirm selection.
If a See pricing link appears next to the counter, your photographer has added prices to the gallery. Just click it.
When you pay
Not while you're selecting. Payment comes up only when you confirm your selection, and it works differently depending on how your photographer takes payments: either you go to a payment page and pay by card or another method offered there, or you see a message that your order goes to your photographer and you settle the payment with them directly.