This is the 13669th most frequent Russian word.
немецко
"Немецко" means "German" (adjective form).
Here, "немецко" refers to the German language and is part of an adjective formation describing a related culture.
Я изучаю немецко языковую культуру.
I study German linguistic culture.
In this case, "немецко" is used in a compound adjective indicating a dictionary related to both the German and Russian languages.
Немецко-русский словарь мне очень помог.
The German-Russian dictionary helped me a lot.
Here, "немецко" is used in an adjectival form to describe something originating from Germany.