Before you get wiped out, take proper measures against summer fatigue and get through summer energetically.
Literal
Exhausted become [before-前に], summer-fatigue measures [object-を] properly do energetically summer [object-を] get-through-[invitation-ましょう].
夏バテ 'summer fatigue/lethargy' — a well-known Japanese health concept for the exhaustion caused by prolonged summer heat and humidity. 対策 'countermeasures.' 乗り切る 'to get through, to weather' — a compound verb of 乗る + 切る ('ride out completely'). ヘロヘロ is a 擬態語 mimetic for being utterly drained, limp, and wobbly with exhaustion — vivid shorthand for the physical state 夏バテ produces.