This is the 67th most frequent Arabic word.
جديدة
"New" (feminine).
Here, 'جديدة' is describing the feminine noun 'فكرة' (idea) in the sentence, following the rules of Arabic adjective-noun agreement.
لدينا فكرة جديدة لمشروع.
We have a new idea for a project.
In this example, 'الجديدة' is an adjective describing 'السيارة' (car), and it comes placed after the noun with the definite article matching between noun and adjective.
السيارة الجديدة تعمل بكفاءة.
The new car works efficiently.
In this sentence, 'جديدًا' is used as an adjective describing the noun 'كتابًا' (book).