LHO has a hand with just too much defense for an opening 3S call. In particular, it probably has an outside Ace. Perhaps something like:
RHO's 2H call almost always shows 5 hears, unless a 2-over-1 must be bid first to show a limit raise in spades. This is confirmed by the diamond following bid. So RHO's hand looks something like this:
RHO's failure to bid clubs at the second turn denies 4 of that suit (unless perhaps 4 little, but that would be amateur), and the failure to rebid hearts denies 6, so the reds are 5-5 or 5-4. The repeated failure to tolerate spades or bid clubs shows the blacks to be 1-3 or 0-3.
RHO's reluctance to spades also infers an absence of aces; this because a couple of Aces, or an Ace and a KQ combination, would be golden to LHO.
LHO might hazard a leave in 3H with two little and diamond tolerance, so I infer a likelihood of 1-2 in the reds.