The abstract is the short version of everything. If you are old like me, it's the elevator speech. Younger scientists, think of this as your TL;DR. You want to tell everyone exactly what you did and what happened, but very briefly. You get about 4 to 5 sentences, under 250 words please!, to introduce, explain why you did it, and finish with what happened and what that means. Wow, this should be 4 killer sentences!
"I tested kidney beans to see how pH impacts germination. I germinated 4 test subjects with different pH over 3 weeks. Normal water with 7.0 pH was best and extremely high or low pH failed. This experiment proved that pH impacts seed germination."
Why an abstract if all the details are also in the Lab Report? Isn't it obvious? Your time as a scientist is important. You ain't got no time to waste reading the whole report UNLESS the abstract catches your interest. Boring, long abstracts get fewer reviews. Yes, science is founded on "social media" concepts of views, likes and followers, only they're called peer reviews, peer verification, and peer references. Your abstract is your #hook.