What is the full form form of planning?

The word 'planning' is the present participle, present tense of the verb to plan (plans, planning, planned).
Example: We are planning a July vacation.

The present participle of the verb also functions as an adjective and a verbal noun (gerund).
Example adjective: The planning phase is complete, now we need the funding.
Example gerund: Good planning is the only way to accomplish your goals.