What is the meaning of the word "Al-Falah" mentioned in the Adhan (Hayya 'ala al-falah), and does it mean jihad or the best of deeds?

"Al-Falah" (salvation/success) is victory, deliverance, and eternal remaining in bliss and goodness. The "Muflihoon" (those who achieve salvation/success) are those who are victorious with everlasting remaining in Paradise. Prayer is a means of victory and deliverance in this world and the hereafter, hence the call to it is a call to al-Falah.