Monday and Tuesday next week are consecutive days off.

Literal

Next-week [possessive-の] Monday [and-と] Tuesday [topic-は] consecutive-holiday [copula-だ].

連休 (れんきゅう) means 'consecutive holidays' — a key concept in Japanese work culture where multi-day breaks (ゴールデンウィーク, シルバーウィーク, お盆) are eagerly anticipated. The sentence is simple declarative but the concept of 連休 carries cultural weight.