The direct experiencing of nibbāna.
Here the text is stating very plainly that insight meditation practice is capable of leading the practitioner to experiencing awakening in this lifetime. At this stage of the Buddhist tradition this was not a far-off goal, as it becomes later on, but was something accessible to anyone who practiced diligently and was willing to make the necessary commitment. Many people were said to have experienced nibbāna during the Buddha’s lifetime. ~ Andy Olendzki
Words of the Buddha: Middle Length Discourses (Satipaṭṭhāna Sutta) Majjhima 10
This is a direct path
for the purification of beings,
for the overcoming of sorrow and despair,
for the going to rest of suffering and sadness,
for the accomplishment of the method,
for the direct experiencing of nibbāna,
that is, the four establishments of mindfulness.
Here a person abides
observing body as body…
observing feeling as feeling…
observing mind as mind…
observing mental objects as mental objects…
ardent, fully aware, and mindful,
leading away worldly yearning and sadness.
Here, a person who has
gone to the forest, or
gone to the root of a tree, or
gone to an empty place,
and having folded the legs around the ankles,
and set the body erect,
one establishes the presence of mindfulness.