Agorima wrote:2. In the second lesson, the words "ten" "ta" "to" are presented as demonstrative adjectives, because the translation is "this" or "that". However they did not mention from the beginning that these words are also articles, translated simply as
Yes, the article does exist in Czech language!
No, it doesn't.
If you use the demonstrative adjective, it can sometimes been translated as "the", but it is still just an expression of an exclamation or emphasis and usually dispensable in the sentence.
"Ten", "ta", "to" are not systematically used as an article and an overuse of these is a stylistic mistake, that will not make a good impression (your writing will look too affected by English. Actually, this happened to me years ago, when I kept overusing ten/ta/to after a return from the UK. And your speaking will look stilted. Not sure whether that's the best English word, it will look as if you were either overly dramatic, or as if you were not too bright and in desperate need of filler words.)