What would you like to know, specifically? Generally speaking these are renowned for the sound quality and versatility. They were designed around 40 yrs ago, originally intended for use in the BBC's vans. They were supposed to hang from the sides and allow monitoring on site at the time. More than one companies manufactured spkrs to the LS3/ 5A design, the Rogers being my favourites.
The mid range is very clear, and the lack of real lower register is compensated by a bloat, so the result is superbly pleasant. For their minimal size they produce outstanding musical results, i.e. a large and very well balanced sound. There is a cult following which means that many parts (or replacements) are easy to source, if expensive sometimes.
Note that the crossover is very complex, and the early models are difficult to drive with an SS commensurate to their size (the ROgers, in particular, are high impedance)-- remember, in those times, tube amplification was still preponderant, and it is easy to drive Rogers LS3/5A with a tube amp.
Think of the sonic origins of Harbeths, Spendors, older ATC... the sound also resembles some of the old panels.
Overall, a marvelous little speaker, objectively limited at both extremes and superseded nowadays by some current offerings -- at a hefty premium, however.
You'd have to check if the drive units are in good shape to gauge what your discovery is really worth (i.e. compute the price of repair if necessary).