If you speak Czech, some English grammar rules will feel natural and others will feel confusing. These are the biggest differences to focus on first.
Czech word order is extremely flexible because grammatical cases identify the role of each word. English word order is fixed because position is the only way to identify subject, verb, and object. Czech speakers must learn to keep English sentences in strict SVO order.
Czech has no articles. English uses 'a', 'an', and 'the' to express whether something is specific or general, known or unknown. Czech speakers must build this grammatical habit from zero.
Czech has a perfective/imperfective aspect system like other Slavic languages. English has no aspect system โ tense alone carries the meaning. Czech speakers must use English tenses to express the completion nuances they express through aspect in Czech.