Generally, things that seem like a saying in English are expected to be translated to the equivalent French saying. Almost all other times you are expected to give a literal translation. Par example: How shall I put it? -> Comment dire ?
The only real exception is when it a direct translation is not grammatically possible, then you have to work with the French grammar in order to come up with the equivalent English sentence. Par example: The women's hats -> les chapeaux des femmes.
Three years after I left a comment, I'm still seeing more comments on this thread... I've been in France those three years, so I can give a definite answer :
Tel is essentially a placeholder adjective for "something" that came before. The confusion comes from this phrase "Tel est mon père" where Tel seems to be used as a noun, which is true. It makes more sense to write the entire phrase as it should be understood : "Un tel homme est mon père" : which would translate to something like "Such a man is my father" or less literally "My father is that kind of man" or "That's the kind of man my father is".
More uses of "tel" here, from which I take the definition which applies to this sentence : http://www.larousse.fr/dictionnaires/francais/tel_telle/77019
Attribut en tête de phrase, a une valeur démonstrative et renvoie à ce qui a été dit précédemment : Tel n'est pas mon avis.
"Used at the beginning of a sentence, has a demonstrative value taken from that which was said before : "Such [or That] is not my opinion."
And of course, tel(s)/telle(s) is an adjective and should agree with the noun being described - so this sentence, even being used as a subject noun, would change to "Telle est ma mère."
And to elaborate - the l' is le, the "neuter pronoun" used as illustrated. It is not usually translated in english except as "so" or "it":
"[le] functions as a direct object referring to an adjective, phrase, clause, or complete statement."
Moi, je crois qu'ils vont gagner le match, et toi?
Je le crois aussi.
"tel ou tel [noun]" is also used as an adjective... if you search the french news, you'll find it used... it seems to mean more like "the particular [noun]" or "the given [noun]" In English we use "such-and-such" as a noun as well as an adjective... not the case for French, it looks like.
Google translate is not accurate to use. It is giving an approximate translation, to give a sense, whereas Duolingo is aiming to teach you the precise words and usage.