After the previous aliyah discussed the way G-d communicated the traveling of the Jews, in this fifth aliyah the Cloud of Glory rises from the Mishkan for their first trip. At this point the Jewish nation had been camped at Mount Sinai for slightly less than a year, and they departed according to the order of the tribes and procedures for the Leviim outlined recently in the Torah.
At this point everyone, including Moshe, thinks they are just three days from entering Israel, and in this aliyah Moshe pleads with Yisro, his father-in-law, to join them and enter Israel with the Jews, but he declines with thanks. At the end of the aliyah the Torah says that the cloud of G-d was over them by day when they set forward from the camp. Rashi says this actually means seven clouds: one in each of the four directions, one above lowering the high places, one below raising the low places, and one before them killing the serpents and scorpions.