In Jainism, Vidyādhars (Vidyādharas) are:

• A special class of human-like celestial beings in Jain cosmology.
• They have bodies like humans but possess extraordinary powers (vidyā) such as flying, changing form, great strength, etc.
• They usually live in specific regions of Jambu-dvīp and nearby dvīps, often in mountains, forests, or cities in the sky (as described in Jain geography).
• In Jain Rāmāyaṇ and other Jain stories, many heroes (like some versions of Hanuman, some kings, warriors) are called Vidyādhars because of these powers.

Are Vidyādhars present in the 5th Ārā?

According to Jain cosmology:

• The type of humans & beings change with each Ārā (era).
• In the 5th Ārā (Pancham Kāl) where we are now,

- Human height, age, and natural powers have greatly reduced. - Beings like Rākṣasas, Kinnars, powerful Vidyādhars etc. as described in earlier eras do not appear on earth in the same visible form now.

• So, in the present 5th Ārā, Vidyādhars as the extraordinary, visibly powerful races described in Jain Purāṇas are considered extinct / no longer manifest here.

However:

• From the Jain view, saṃsār (cycle of birth) is beginningless and endless. The jīvas (souls) that once took birth as Vidyādhars still exist; they now take other forms according to their karma.
• In future cycles (next avasarpinī/utsarpinī and earlier Ārās) such Vidyādhars will again appear when conditions become suitable.

So in simple words:

• Who are Vidyādhars?

Celestial-human races with special powers (vidyās), often appearing in Jain Purāṇic stories like Jain Rāmāyaṇ, living in special regions of Jambu-dvīp etc.

• Are they available now in 5th Ārā?

No – in our present Pancham Kāl, those kinds of Vidyādhars do not appear on earth; they are treated as beings of past and future eras, though the souls who were once Vidyādhars continue in saṃsār in other forms.

You can read connected explanations (e.g., about Jain Rāmāyaṇ where Vanars are described as Vidyādhars) here: