sri-bhagavan uvaca
pasya me partha rupani
sataso ’tha sahasrasah
nana-vidhani divyani
nana-varnakritini ca

"The Supreme Personality of Godhead said: My dear Arjuna, O son of Pritha, see now My opulences, hundreds of thousands of varied divine and multicolored forms."

From now on Sri Krishna speaks. Earlier Arjuna revealed his understanding of the Lord's sermon, and further expressed his deep desire to see the Lord as revealed by Him. Sri Krishna wanted to fulfil his desire. In the next Four slokas [5,6.7 and 8], the Lord assures Arjuna that He would reveal His Viswaroopam. Being a very precious and rare sight, the Lord is not immediately showing; but makes a preamble before the greatest show. Partha = Arjuna!, me = My [Sri Krishna's], rupani = various images, pasya = look. Satasa = Hundreds of them, sahasrasa = thousands of them. Nana vidhani = variety of [images], divyani = Divine and wonderful, nana varna = variety of colors, akritini = sizes and shapes. Swami Vedanta Desika in his Tatparya Chandrika says that Arjuna had not yet seen the Viswaroopam; but, the Lord mentions 'look'. This is to encourage and enthuse Arjuna to be ready to look at the Viswaroopam He is going to reveal, which could be seen after Arjuna was gifted with the divine vision to see. The Lord's images are at various places like in Sri Vaikuntam as Param, in Tirupparkadal as Vyuham, at various times as Vibhavam, in many Kshetrams as Archa and in the hearts of people as Antharyami. In every category, the Lord is in Hundreds and Thousands of forms. In Vyuham, the Lord is as Sri Vasudeva, Sri Sankarshana, Sri Aniruddha and Sri Pradyumna. Vibhavam means many Avatars of the Lord. Kshetrams are in Thousands. Nana vidham means the identity of each Roopa varies. Some are with Two arms, Four arms, Eight arms, Sixteen arms, Varada hasthamAbhaya hastham, etc. By saying divyani, the Lord tells Arjuna that he could never imagine. The Images would be pure satvam unlike the mixture of satva, rajas and tamas, we normally see. Images would display a variety of colours. Shapes and sizes are different, like Fish, Turtle, Boar, etc. 
                                                                                                   (continued)