The concept of the guna is linked with Prakriti or nature.
One of the most widely used words, ‘guṇa’ has several
senses such as quality, rope, bow-string, nature and certain letters
of the Sanskrit alphabet used in grammar. However, in the Indian
philosophical systems such as Sāṅkhya, Yoga and Vedānta it refers to
the three fundamental components of prakṛti or pradhāna or māyā, the
basic matrix out of which the physical universe is created.
These guṇas are three in number: sattva, rajas and tamas.
They are not qualities or attributes in any sense, but fundamental
subtle substances or elements which constitute the prakṛti like three
cords making a rope.
The existence of these guṇas is inferred from the qualities presented
in the created world. Sattva is responsible for knowledge and
pleasure. Rajas is responsible for activity and passions. Tamas
produces indolence, sleep and evil.
Before creation, these three are in a perfectly balanced state. At the
beginning of creation, this balance is upset and evolution of the
A Concise Encyclopedia of Hinduism by Swami Harshananda
Saguna Brahman is Brahman with guna and the implication is that it is Brahman relative to the universe. If Saguna Brahman does not have form or akara then how can it have gunas which are constituents of form? Gunas are actual subtle substances. How will gunas operate without a form?
Nothing positive can be said about Nirguna Brahman precisely because it has no guna.
Nirguna Brahman according to Yajnavalkya
Yajnavalkya said: O Gargi, it is the
supreme being that the non-yogins call gross but, in fact, that is
eternal and wonderful lord; one that is not long, not red, that has no
head, that has no setting, hence that has a lasting taste, that has no
contact, no smell, no juice, no eyes, no ears, neither speech nor
mind, no brilliance, no proof [or magnitude], no (worldly) happiness,
no name, no race, no death, no age, no ailment; that is nectarine,
that is expressed by the word Om, that is immortal, that has neither a
predecessor nor a successor, that is endless and non-external. It eats
something. It does not eat anything. ..
Linga Purana II.9.53–54
Thus we conclude that Saguna Brahman is also sakara.