Here are some examples from dictionaries where hope is used in the plural
people have hopes of increasing trade between the two regions (Collins Cobuild)
she has hopes of studying to be a nurse (LDOCE)
he secretly cherished hopes that George would marry his daughter (OALD)
His early hopes of freedom were now gone.
Hopes are high that a resolution to the conflict can be found.
Hopes of a peaceful end to the strike are now growing.
Hopes for the missing men are fading.
Here are also some dictionary examples in which hope is used as an uncountable noun, hence in the singular form:
Hope faded after wrecked remains of the ship were washed onto the shore.
Hope remains that survivors will be found.
the treatment gave him renewed hope
I didnʼt give up hope of being released.
I donʼt hold out much hope of finding a buyer.
I am wondering why ‘hope’ is sometimes used in the plural while otherwise in the singular. Or, is there any guideline as to when hope should be used as uncountable and when as countable in the plural? Could anyone help on this? Many thanks in advance!