The way the correlatives tiel and kiel are used here took me a long time to understand, so here's my interpretation (full disclosure, I'm not an expert).
At first I thought the sentence would translate to "She does not act that way well how you." That really doesn't make sense.
Correlatives are just words that perform a single function in a pair. For example in "I like neither wasps nor hornets", neither and nor are correlatives. Understanding that, I still was confused how question words (the correlatives starting with k) are considered correlatives, because they always seem to be used alone.
However, I found that many romance languages phrase relative clauses in a way like this: "I eat that, what you eat.", where it would normally be "I eat what you eat" for English speakers. Additionally, I thought about how demonstratives sometimes can modify the word that follows.
So, I ended up with a better translation, "She does not act that well how you act", by letting the 'agas' verb be implied after 'vi'. This is awkward, but at least it makes sense. Hopefully this helped somebody other than me understand this usage of tiel and kiel. Corrections or additional explanations are always appreciated.
Ultimately, as one learns Esperanto, one will need to learn to express (and understand) words. Of course "She does not act that way well how you" doesn't make sense. It's not English and it's not Esperanto.
For those still in translation mode, simply accept and learn that "tiel... kiel..." is a pattern that often translates to "as... as...". In that case, your literal translation becomes She does not act as well as you" - which is also the correct translation.
For those who want to know why it means "as... as..." - think of it as She does not act well in that way in which way you do."
I think of it as: She does not act .. the good way, the way you do.
(.. added for clarity)
As in, "kiel vi" is a subordinate clause describing "tiel bone." It's like a combination of:
"Ŝi ne agas tiel bone." and "Ŝi ne agas kiel vi (agas)."
It also makes me think you could omit tiel, but that is just an English-centric way of thinking.
BlazeCyndaquil, there are some useful constructions where correlatives act together as a pair, like tiel and kiel do in this example.
But they often act alone, too! "Kiel vi estas?" uses the correlative kiel alone.
They're the question and answer words, and in Esperanto, they're constructed in a systematic way. Here's what the Esperantist Don Harlow had to say about them: "Correlatives are the words used to ask questions which require specific answers -- the "who, what, when, where, how" of a language, and their general answers ("there, here, everywhere, nowhere, somewhere")."
Much more here, plus the chart that tells you how to construct them: http://literaturo.org/HARLOW-Don/Esperanto/correlatives.html
Yes, it's a pity the English translation is not given as "She does not behave as well as you". Yes, I know there is another Esperanto verb, "konduti" for "behave", but in English, the sentence "She does not act as well as you" would normally refer to what an actor does on the stage, which would be "aktori" in Esperanto.