来週お邪魔したいのですが、何曜日ならご都合がよろしいでしょうか。

、。

I'd like to drop by next week — which day would be convenient for you?

Literal

Next-week honorific-bother-want-[explanatory-のです]-but, what-day-of-the-week [if-なら] honorific-convenience [subject-が] good-[polite-でしょうか].

お邪魔する (literally 'to humbly intrude') is a set expression for 'drop by / visit' with self-effacing politeness. 都合 ('convenience / circumstances') is a core scheduling word. よろしい is a respectful いい. The whole sentence is high keigo, typical of polite business or formal social scheduling.