、。
That guy today is way too eccentric — I just can't keep up.
Literal
Today [attributive-の] that-guy [topic-は], too-eccentric-[te-reason-くて] cannot-keep-up.
アイツ ('that guy, that one,' katakana for slang emphasis) is the rough, distancing third-person reference. エキセントリック ('eccentric') is a katakana loanword. ついていけない is the potential-negative of ついていく ('to keep up with') — 'cannot keep up.' The over-the-top loanword エキセントリック paired with the casual アイツ creates a stylized, slightly comedic complaint.