Tags are like keywords that describe your video and help people find them more easily. By creating the right tags, people can search for these terms and your video will show up in the search results. When you add them however, YouTube sometimes makes them single words, rather than phrases which is not ideal.
You want to be more specific with your tags to attract the right users. To use multiple word tags, put them in quotes.
For example if you were promoting red boots, and both red and boots were separate tags, then you would get listed with thousands of unrelated videos that could be about anything red or about boots.
By having the tag “red boots” in quotes will make your video more targeted and have a better chance at showing higher up in Youtube’s search results. That is because there will be a lot less competition for that tag than for the single word tag.
Also because you will be targeting the right audience, you are more likely for them to click through to watch your video which is the whole purpose of adding your video on YouTube to begin with.
