First of all, I must appreciate your eagerness to learn new stuff (though it makes it harder to explain). I will try my best to explain in a way you can understand.
You might have been taught about eletron filling order like: 2 electrons in K shell, 8 electrons in L shell and so on. However, that works only up to a certain level.
Its a fact that each shell itself is composed of subshells (experiments involving spectra have shown this). The number of subshells each shell has depends on the number of the shell (like 1st shell, 2nd shell; a.k.a principal quantum number). These subshells are called as s, p, d, or f. The s-subshell can fit 2 electrons, p-subshell can fit a maximum of 6 electrons, d-subshell can fit a maximum of 10 electrons, and f-subshell can fit a maximum of 14 electrons. The first shell has only an s orbital, so its called as 1s. Since it can have either one or two electrons, its called as $1s^1$ and $1s^2$ respectively. They are also the respective "SPDF" configurations of hydrogen and helium. In this way, you would consider the electronic configuration of oxygen to be $1s^22s^22p^4$.
Another important point to note, is that the filling of electrons in subshells doenst actually fill from low to high. There is a special rule called aufbau principle (german word for 'building up'). Here is a diagrammatic representation of aufbau principle:
This infact, is the actual way of writing an electronic configurations. Schools teach to primary classes the 'configuration-per-shell' method simply because its easier and they usually dont come across geniuses like you. Now, I think you can understand the 'SPDF' configuration much better.