When spread, an eagle's wingspan can reach up to a meter.
Literal
Eagle [possessive-の] wing [topic-は] spreading-[if-と] 1 meter [even-にも] becomes.
A fact about eagles. 鷲 (わし) 'eagle'. 羽 (はね) 'feather, wing' — here means the full wingspan. 広げる ('to spread, open out'). メーター is an alternative katakana for メートル ('meter') — slightly dated usage. ~にもなる ('reaches even X, becomes as much as X') uses にも to express the surprising magnitude.