Your computer has a spell check, but it doesn’t have a telepathy check. In English we have many homonyms: words that sound alike, but have different spellings and meanings. For example: pair of genes are responsible for your DNA, but a pair of jeans are what you wear. Computers can’t (yet!) correct a mistake in vocabulary.
English is indispensable for your education, careers and self-edification. Learning keeps you young. The English you speak and write tomorrow is the English you study today.