Again, be sure to read about TBCs, too!
What is a TBC? Time Base Correction for Videotapes
Timebase correctors are not format converters. Timebase correction has nothing to do with converting video from PAL to NTSC (or vice versa).
In order to play a PAL tape, you need a PAL VHS player.
To play SECAM, you need a SECAM player.
There are also "multi-format" VCRs that can work well.
And if you're interested, I have one multi-format VCR available, a Panasonic AG-W2 (Samsung 5000W clone!) in excellent condition, for $250 plus shipping ($10-15?). It plays PAL tapes quite nicely. Not tested it for SECAM, no SECAM tapes to test with. NTSC playback isn't great, average VHS quality. But the reason to have this would be to play PAL tapes anyway! And if you want, yes, it can convert PAL/SECAM to NTSC. I prefer to just make PAL DVDs from PAL VHS tapes, but this will convert the signal in-VCR, should you want that. These decks were $600+ when new. Decks like this are no longer made, and I'm asking for quite a bit less ($50-100) than eBay auctions on same-condition models.
Timebase correction is intended for "signals" moreso than any specific format. But it is specific formats that exhibit more or less errors than others. VHS tapes, for example, have an enormous amount of signal errors. DVDs, on the other hand, have few to none. Laserdiscs don't have too many errors to worry about, but signal correction from a TBC won't hurt.