及 (jí) here means 'to reach / catch up to' - so literally 'no one can reach (them)'. Often used after a noun phrase describing a peak ability or achievement. Near-synonyms:
无人能比 (wúrén néng bǐ, no one to compare),
独一无二 (dúyī wú'èr, one of a kind),
出类拔萃 (chūlèi bácuì, head and shoulders above).
