Complex sentence: Unsigned Lah numbers have an interesting meaning in combinatorics: they count the number of ways a set of "n" elements can be partitioned into "k" nonempty subsets that are linearly ordered.
Split into simpler sentences: Unsigned Lah numbers have an interesting meaning in combinatorics. Namely, they count the number of ways a set of "n" elements can be partitioned into "k" nonempty subsets that are linearly ordered.