Student or Learner
[...] those [masculine nouns] that are very common, such as the second example below, are used in many everyday expressions, and will thus be assimilated without great difficulty.
as in the case of the masculines, there are a few basic nouns that fall into this category, such that their acquisition and assimilation will be accomplished with little extra effort on the part of the learner.
(Ukrainian: A Comprehensive Grammar; Stefan M. Pugh and Ian Press)
As far as I can comprehend the text above, the nouns that are very common, or, in other words, basic ones, should pose no great difficulty to the learner to learn them (will thus be assimilated without great difficulty). I suppose 'with little extra effort' should mean almost the same here.
But does it always have this connotation, can't it mean something closer to 'with some extra effort'?
not a teacher
(1) "It can be accomplished with little extra effort." Not much extra effort is required.
(2) "It can be accomplished with a little extra effort." It requires a certain amount of extra effort, but again, not a lot.
(1) Emphasizes the small amount of effort needed.
(2) Emphasizes the need for at least some effort.