Many teams adopt Scrum but still approach development the same old way. Build widget A in Sprint 1, build B in Sprint 2, and build C in Sprint 3, and in Sprint 4, we put A+B+C together. In Scrum, a Product Increment is whatever you previously built, plus anything new you built in this last Sprint (the increment).
An Increment is a concrete stepping stone toward the Product Goal. Each Increment is additive to all prior Increments and thoroughly verified, ensuring that all Increments work together. In order to provide value, the Increment must be usable.The 2020 Scrum Guide
So, in Scrum we build widget A in Sprint 1, we build B and connect it to widget A Sprint 2, we build C and connect it to A+B+C in Sprint 3. When we build things iteratively and incrementally, we always have a working version of our product running all the time. We always improve on what we already have and then add to it. If you are doing something only once, you are not iterating. If you are not adding to what you already have, you are not incrementing.