In "La Belle Dame Sans Merci," please give me the description of the knights of unfortunate conditions.

I am not entirely sure whether I understand your question
correctly. By asking about the "knights of unfortunate conditions," are you refering to
the other knights that the knight who tells us about his experience with the lady dreams
about? These figures are seen by the knight as he falls asleep with his lady, and
obviously there appearance foreshadows the impact that his love for the lady will have
on him and also gives the reader an important warning about the dangers of being taken
in and deceived by a femme fatale figure. Note how these figures are described in the
poem:

I saw
pale kings, and princes too,

Pale warriors, death-pale were
they all:

They cried--"La Belle Dame sans
Merci

Hath thee in
thrall!"

I saw their starved lips in the
gloam

With horrid warning gaped
wide,

And I awoke, and found me
here

On the cold hill
side.

Note the way that these
figures are described as being "pale" and "death-pale," which should make us think of
the way that the knight of the poem is described in the first stanza as "Alone and
palely loitering." Not too the way that "their starved lips" are pictured as another
sign of the distraction that they suffer. They are so focussed on love that it appears
they have little appetite and are slowly wasting away. In spite of this timely warning,
the knight has become yet another victim to La Belle Dame Sans Merci, and is suffering
in the same way as a result from the sickness of unrequited love, as so many men have
done before him.