Most likely (because anything is possible), the two black wires going into one end of the switch (back stab and screw next to it) are "incoming hot" and "pass-through hot". All neutrals (white) are together (which is good) and all groups (bare copper) are together (which is required).
If your new smart switch has screws:
- Line/hot/incoming power = connect to the two black wires. If the new switch is designed to have two wires under the screw (clamp rather than just a screw) then you can use that. If it does not, then even if it has a backstab option, connect a short piece of black wire to the existing two wires with a wire nut and connect the other end of that piece (pigtail) to the new switch.
- Load = connect to the single (top in the picture) black wire.
- Neutral = connect to the white wires. You will need to add a short piece of white wire to the existing bundle of neutrals. You may need a new and/or larger wire nut to do that (now might be a good time to pick up a pack of wire nuts - you never know when you will need one).
- Ground = use a short piece of green or bare wire and add it to the existing bundle of grounds.
If your new smart switch has wires:
- Wire nut the line wire (likely black) to the two existing black (bottom) wires.
- Wire nut the load wire (likely red) to the top black wire.
- Wire nut the neutral wire (white) to the bundle of neutrals.
- Wire nut the ground wire (green) to the bundle of grounds.
Older simple switches (like yours) often don't have a ground connection, which is OK.
New, especially smart, switches can (generally) ground directly to the box instead of using a separate wire. However, that only works with a metal box. You have a plastic box, so connect ground to either to a ground wire (if supplied) or ground screw (should be clearly marked, and probably green).