Hex-Rays is actually a plugin for IDA Pro, developed by the same company that creates IDA Pro. The most notable plugin from Hex-Rays is the decompiler, which adds the capability to decompile certain types of binaries directly within IDA Pro. This decompiler can automatically generate C-like pseudocode from the disassembled code, making reverse engineering significantly easier.
(Exact contents require extraction and inspection; I assumed typical items for this naming pattern.)