The word order in the sentence has been changed probably for emphasis. The sentence could be rephrased to:
Of course, the fact that ... is implied in this description"
The preposition "in" is used to go with the noun phrase "this description" and it has nothing to do with the verb to imply. To imply is a transitive verb which means:
Indicate the truth or existence of (something) by suggestion rather
than explicit reference
To imply is not used as an intransitive verb and "something implies from something" is not a grammatical construction as the verb doesn't take an object . It should be "something (the fact) is implied in something (this description)" or "he/she/they, etc. implied something (the fact) in something (this description)".