A bit of background
There are 26 letters in the English language, but 44 sounds. This is part of what makes English such a tough language to learn.
We can do our best to help our kiddos learn all of the spelling rules, but there will always be words that break the mold.
Word lists were created to help us teach kids high frequency words that don't follow normal spelling rules OR words that kids will encounter early that make sense for them to know, even if they do follow the rules (ex. here, at, had). Kids will need those basic words to understand basic books.
Some districts use Dolch, some use Fry and others use Fountas and Pinnell. If you want to know more about why, read this.
Dolch Sight Word Lists
Fry Word Lists
Fountas and Pinnel Word Lists
Sight Word Games - Resources online
In school, your child's teacher will make a word-list wall in the classroom. After the kids learn the words in class, the word goes on the wall so kids can reference it during the day.
You can do the same at home.
You can make the word wall anywhere, including right by where your child usually reads or does homework. Just write one word on an index card and tape it to the wall. Repeat until you've got all the words you've worked on up on the wall. Keep adding over time. You can also add words that are not on the sight word lists, but just words that you've worked on together.