The Threefold Lotus sutra is a pretty heavy sutra to start on, weighty words, and lots of metaphors and parables in there!
The vimalakirti sutra is pretty easy to read.. some heavy content but the text is not complicated to read
I found reading the texts of the early zen masters, the Patriarchs and the like, helped me personally come to terms with what the sutras were trying to say, but this is just my own mind
Here, Try the Heart Sutra, it's short and simple (Ha! But it does get right to the heart of the matter. 5 heaps are usually called skandhas or aggregates)!
Heart Sutra - short version (translated by Edward Conze):
Homage to the Perfection of Wisdom, the Lovely, the Holy!
Avalokita, The Holy Lord and Bodhisattva, was moving in the deep course of the Wisdom which has gone beyond. He looked down from on high, He beheld but five heaps, and he saw that in their own-being they were empty.
Here, Sariputra, form is emptiness and the very emptiness is form; emptiness does not differ from form, form does not differ from emptiness; whatever is form, that is emptiness, whatever is emptiness, that is form, the same is true of feelings, perceptions, impulses and consciousness.
Here, Sariputra, all dharmas are marked with emptiness; they are not produced or stopped, not defiled or immaculate, not deficient or complete.
Therefore, Sariputra, in emptiness there is no form, nor feeling, nor perception, nor impulse, nor consciousness; No eye, ear, nose, tongue, body, mind; No forms, sounds, smells, tastes, touchables or objects of mind; No sight-organ element, and so forth, until we come to: No mind-consciousness element; There is no ignorance, no extinction of ignorance, and so forth, until we come to: there is no decay and death, no extinction of decay and death. There is no suffering, no origination, no stopping, no path. There is no cognition, no attainment and non-attainment.
Therefore, Sariputra, it is because of his non-attainmentness that a Bodhisattva, through having relied on the Perfection of Wisdom, dwells without thought-coverings. In the absence of thought-coverings he has not been made to tremble, he has overcome what can upset, and in the end he attains to Nirvana.
All those who appear as Buddhas in the three periods of time fully awake to the utmost, right and perfect Enlightenment because they have relied on the Perfection of Wisdom.
Therefore one should know the prajnaparamita as the great spell, the spell of great knowledge, the utmost spell, the unequalled spell, allayer of all suffering, in truth - for what could go wrong? By the prajnaparamita has this spell been delivered. It runs like this:
Gate gate paragate parasamgate bodhi svaha
(Gone, gone, gone beyond, gone altogether beyond, O what an awakening, all-hail!)