Quietly drifting in no particular direction. That's what the doldrums mean to me, based on vague memories from high school history classes of the great explorers in their sailing ships . (Confirmed by Wikipedia it's apparently an area near the equator, famously described in the "Rime of the Ancient Marine" by Samuel Taylor Coleridge.)
For business it often means a quiet period too. Everyone is enjoying their family holidays or summer recreation activities rather than starting new business activities.
But it can also be an opportunity to spend more time building stronger client relationships because there is less pressure and conversations can be more relaxed and informal. It may be a good time to reflect, plan and strategize with key customers before the hectic season of "back to school" arrives. Trying to fit in some social contact with customers during the summer doldrums may help you be more successful during the winter flurries of activity that follow.