expression
for the first time in several months
Expresses that something is happening after a gap of several months. Often used with 〜する or 〜だ to indicate the first occurrence in that period.
何ヶ月ぶりかに友達と会った。
I met a friend for the first time in several months.
何ヶ月ぶりかの雨で、庭の植物が生き返った。
With the first rain in several months, the garden plants revived.
久しぶり is a general expression for 'after a long time' without specifying the duration. 何ヶ月ぶりか explicitly mentions 'several months'.
Combination of 何 (what/how many), ヶ月 (counter for months), and ぶり (after an interval), with the question marker か. The ヶ is a simplified form of 箇.