Sight words (also known as 'high-frequency words') are some of the most commonly used words in the English language.
A good basic knowledge of these is very important for fluent reading. This can be achieved through a variety of word-games, flashcards and even sight words apps.
Attached is a link you might find useful, to learn more about sight words.
https://ncse.ie/wp-content/uploads/2023/11/DolchWord_List_220.pdf