If you're a writer, you may have come across the phrase passive voice. You may ask yourself, why is it a bad thing? The answer is, it isn't always. There are always exceptions to the rule. That being said, using active voice will often strengthen your writing and make it more direct.
Active voice is when the character acts upon the verb. Which means the character comes first in the sentence.
The watcher overlooked the scarlet stains of his ugly deed as they blended with his dark clothes.
Herveus crafted the sword.
Passive voice is when the character is acted upon, so comes last. And sometimes the character is omitted all together.
The scarlet stains of his ugly deed blended in with his dark clothes and were overlooked by the watcher.
The sword was crafted by Herveus.
If you have trouble spotting the difference between passive and active voice, there are many apps out there which can help you. You can find one I have found to work well for myself at https://prowritingaid.com
There is a paid and free option. The main difference is you can only check smaller passages at a time with the free version.