This is the 689th most frequent Czech word.
plánu
"Plánu" is the genitive or accusative singular form of "plán," meaning "plan" in English.
In this sentence, 'plánu' is used in its accusative singular form, referring to 'a plan' as the object of the verb 'mám' (I have).
Mám skvělý plánu na víkend.
I have an excellent plan for the weekend.
Here, 'plánu' is used in its genitive singular form to indicate possession or association with the noun 'podle' (according to).
Podnikli jsme cestu podle plánu.
We went on the trip according to the plan.
In this example, 'plánu' appears in its genitive singular form to illustrate an indirect relationship expressed by 'na základě' (based on).