What is this component? Please and thank you
That is a variable inductor.
thank you
And, by the way, they are not useful in hobby electronics. They're relevant for old school analog video (and sometimes audio) stuff, to tune it to work at the correct frequency. The turning process (ie, adjusting each one just right) is quite complex, typically done in a precise order during the manufacturing process.
Theres an old joke about those. A guy is having a problem with his TV, tries to fix it himself and calls their help line. "So I opened it up, and there were all these little cans with screws in them, and they were all loose, so i tightened them all down. And now it really doesnt work"
Anyway, when you're scrapping shit and you see a bunch of those, it generally means you wont tine anything worth salvaging, at least not in that part of the board.
DrAzzy:
And, by the way, they are not useful in hobby electronics. They're relevant for old school analog video (and sometimes audio) stuff, to tune it to work at the correct frequency. The turning process (ie, adjusting each one just right) is quite complex, typically done in a precise order during the manufacturing process.
Nothing directly to do with video or audio. These are IF tuned circuit "cans" as part of the superheterodyne receiver circuits, may or may not include the capacitor internally.
Don't know however what it is doing amidst a sea of electrolytic capacitors. 
If you wanted a serious answer, you would need to tell what this particular piece of equipment is. 
DrAzzy:
There's an old joke about those. A guy is having a problem with his TV, tries to fix it himself and calls their help line. "So I opened it up, and there were all these little cans with screws in them, and they were all loose, so i tightened them all down. And now it really doesn't work"
And cannot be recovered!
Good one! 
The number of pins from it on the underside of the pcb will tell if its a simple inductor (2 pins) or a transformer (4 or more).
Paul__B:
Don't know however what it is doing amidst a sea of electrolytic capacitors.
Often those boards have SMD parts on the other side - so there may well be other components connected to it besides those caps. It looks like consumer grade audio/video/radio stuff from the analog era - maybe from a TV, VCR, or tuner.
DrAzzy:
It looks like consumer grade audio/video/radio stuff from the analog era - maybe from a TV, VCR, or tuner.
That was my thought, but I greatly doubt it would have SMD parts as it is single-sided (and indeed, phenolic). In fact, you may note it has TO-92 transistors.