Normally, the person who invited the guests carves the roast at the table.
Literal
Usually [topic-は] guest [object-を] invited person [subject-が] dining-table [at-で] roast-meat [object-を] cuts-and-divides [polite-ます].
お客を招いた人 is a relative clause: 'the person who invited guests.' 切り分ける is a compound verb: 切る (cut) + 分ける (divide) = 'to carve.' A sentence about hosting etiquette.