Tina wants to install pine flooring in an unheated cottage. Different lumber yards were talking about curing the pine for as much as a year before installing it.
Getting wood to a stable moisture level is important for flooring and if it is locally milled you must either kiln dry it, or air dry it for at least a year. Pine has the additional problem of resins that tend to come through knots and cause finishing problems and air drying is the only to stabilize these resins. If the flooring comes from a manufacturer, you can usually be assured that it is properly cured and dried before it gets to your cottage.
Even with all of these preparations, real wood floors in a radically variable environment, like an unheated and only occasionally occupied cottage can cause nice floors to buckle from too much expansion. (Grandpa's old cottage floors were rough sawn lumber with good gaps to avoid problems.)
New "engineered" flooring has a stable plywood base with all kinds of veneers on the top, including the Pine that Tina wants. The tongue and groove pieces glue together and float over the main floor, which means that it is unaffected by humidity and temperature changes. The whole floor will expand and contract as one single piece, moving very little and only at the edges. This avoids buckling. There are many variations, and differences in quality available on the market. Where there is no serious moisture problem, you can use ones that have a press-board base. Where moisture is a problem use the ones with a plywood base. The decorative veneers have different thickness (how many times can you sand it), and even some that are photographic plastic laminate finishes like your kitchen counters. Shopping around is important, but all of these new "engineered" floors are more stable than the standard massive wood floors.