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It's a two-seater sofa upholstered in stain-resistant synthetic leather.
Literal
Dirt [to-に] strong synthetic-leather [object-を] used 2-person-seat [of-の] sofa [copula-です].
Product-catalog register. 汚れに強い = 'resistant to staining,' using に with 強い in the sense 'strong against/resistant to.' 合成皮革 is a compound of 合成 ('synthetic') + 皮革 ('leather/hide'). ~掛け attached to a number is a seating-capacity counter ('for X people to sit'). 使用した is a past-tense relative clause modifying 合成皮革. The whole sentence is a noun phrase + copula — the standard product-description structure.