MS- Words also helps you to reviewing your spelling and grammar mistake in your documents. With Word spell check tool you can check and correct your grammar mistakes.
Click on Review tab at the top and select the Spelling and Grammar button. Its helps you to find out misspelled word and shows them in right side panel. Place your cursor over it and correct them. Red line under a word show that it a spelling mistake and you have to correct it.
If you are sure that the spelling is right then click on Ignore it button unless change it. Grammar mistake are indicated with the help of green or blue line under the word or sentence.