Adjective predicate construction:
压力 'pressure' +
大 'big' = 'pressure is big'. Chinese routinely uses
大/
小 with abstract nouns where English uses adjectives like 'high/low' or 'a lot of':
风险大 'high risk',
收入大 'high income'. The pun
压力山大 ('Mt. Pressure / Alexander') comes from this phrase.