Sura means Devata, Esha means the Ruler, So Sureshah means the ruler of the demi-gods. Krishna, The Supreme Personality of Godhead is the ruler of all these demi-gods.
na me viduḥ sura-gaṇā prabhavaḿ na maharṣayaḥ
aham ādir hi devānāḿ maharṣīṇāḿ ca sarvaśaḥ (BG 10.12)
“Neither the hosts of demigods nor the great sages know My origin or opulences, for in every respect I am the source of the demigods and sages.”
All the powers which rest with the demi-gods and mystics are provided by Lord Sri Krishna, the Supreme Personality. All these powers have a limitation and hence it is difficult for them too to understand how Krishna appears from His own internal potency.
All the demigods are also Jivatmas or ordinary living creatures whom Lord Krishna, the Supreme Personality has empowered by giving them special powers to represent Him to manage the Universe. Brahma is the foremost among the demigods- with the task of creation within this material world. Indra is incharge of rains, Varuna for water, Surya for sunshine, Chandra for moonshine, Vayu for air, Agni for fire and so on. The demigods are thirty three crores totally. Each with a designated task and all of them live in the upper planets called svarga loka or heaven. Demigod means the devatas.
Ekale isvara Krishna, ara saba bhritya: (Chaitanya-caritamrita Adi 5.142)
Only Krishna is the Supreme Personality of Godhead.
sūta uvāca
yaṁ brahmā varuṇendra-rudra-marutaḥ stunvanti divyaiḥ stavair
vedaiḥ sāṅga-pada-kramopaniṣadair gāyanti yaṁ sāma-gāḥ
dhyānāvasthita-tad-gatena manasā paśyanti yaṁ yogino
yasyāntaṁ na viduḥ surāsura-gaṇā devāya tasmai namaḥ (SB 12.13.1)
Sūta Gosvāmī said: Unto that personality whom Brahmā, Varuṇa, Indra, Rudra and the Maruts praise by chanting transcendental hymns and reciting the Vedas with all their corollaries, pada-kramas and Upaniṣads, to whom the chanters of the Sāma Veda always sing, whom the perfected yogīs see within their minds after fixing themselves in trance and absorbing themselves within Him, and whose limit can never be found by any demigod or demon — unto that Supreme Personality of Godhead I offer my humble obeisances.
Lets chant the Holy Hame of the only Supreme Personality and seek Him to empower our intelligence to offer our Devotional service to Him by understanding the position of the devatas/demi-gods.
Nama 86 – VishnuSahasranama