na-adjective
Describes something that only concerns the surface or outward appearance, lacking depth or thoroughness. Often used for understanding, relationships, or analysis.
彼の知識は表層的で、深い議論にはついていけない。
His knowledge is superficial, so he can't keep up with deep discussions.
We only have a shallow relationship.
浅い is a more common, everyday word for 'shallow' (literal or figurative), whereas 表層的 is more formal and analytical.
Compound of 表層 (surface layer) + 的 (-like, -ish). The exact historical derivation is uncertain, but the word follows a common pattern for forming adjectival nouns from nouns.