It's "title case", which is typical of American style in headlines, etc. British English tends not to use it nowadays. Note also that there is no verb in your title. In titles, headlines, etc., we usually omit function-words such as "to be", prepositions, and articles. This abbreviated style saves valuable space for the more important words.

Yoshi San! That’s a really good question. It can help if you tell us where you saw this sentence written like that. I think that the reason the first letter is capitalized is because it’s on a sign or advertisement and it’s trying to get your attention. Also, in movie and book titles the first letter is always capitalized except words like “the”, “of”, “and”. I hope this answers your question. 頑張って😃

This is called title case, and it's used for headings/article etc to make them stand out. It's not used for the main text of an article. It's used just because it's pretty/makes things look more important. There's no other reason. You can use normal capitalisation as well, and there's literally no difference. However, if you are seeing title case in a newspaper/magazine or academic paper, it may be because the style guide requires it. Again, there's no logical reason, except to make things stand out.

Hi Yoshi, Sometimes, for titles of articles or in advertisements, people will put all initial letters of nouns/verbs as capitals just to get your attention. All prepositions (like "for" and "the") are lower case letters. I hope this helps! Let me know if it's still unclear.