Sorry, I forgot the cardinal rule of acronyms: Put the full text at least once, associated with the acronym, so people don't have to go look stuff up.
(Then again, looking stuff up can be highly instructive.)
Anyway, OODA stands for Observe, Orient, Decide, Act.
Theory is that before you can act, you have to decide to act.
The decision is based on orientation, or assimilation and partial processing of things observed.
Orientation requires observation, IE you can't assimilate and process facts you never notice.
Getting inside the enemy's OODA loop used to be a focus in a lot of military training.
Now, back to our regular programming....