noun which may take the genitive case particle 'no'
Indicates a small, indefinite number of countable things. Used as a noun or with の to modify another noun.
There are a few eggs in the fridge.
Please answer a few of the questions.
We have to solve several problems.
There are a few apples on the table.
I bought a few souvenirs at the shop.
若干 is a more formal, written-style word for 'a small number/amount', while いくつか is the everyday spoken equivalent.
いくつか is a colloquial general word for 'a few (of something)' usable on its own, while 一二 typically attaches directly before a counter, as in 一二日.
たくさん means 'many/a lot', the opposite quantity from いくつか's 'a few/several'.
Combination of いくつ (how many) and the question particle か, which here functions to create an indefinite expression.