Satrughna killed a Raksasa named Lavana, who was the son of Madhu Raksasa. Thus He established in the great forest known as Madhuvana the town known as Mathura

Expressions researched:
"Satrughna also killed a Raksasa named Lavana, who was the son of Madhu Raksasa. Thus He established in the great forest known as Madhuvana the town known as Mathura" |"Satrughna killed a demon named Lavana at Madhuvana and thus established the capital of Mathura"

SB Canto 9

Śatrughna killed a demon named Lavaṇa at Madhuvana and thus established the capital of Mathurā.

SB 9.11 Summary:

When Bharata went out to conquer various lands on behalf of the emperor, Lord Rāmacandra, He fought many millions of Gandharvas. By killing them in the fight, He acquired immense wealth, which He then brought home. Śatrughna killed a demon named Lavaṇa at Madhuvana and thus established the capital of Mathurā.

Śatrughna also killed a Rākṣasa named Lavaṇa, who was the son of Madhu Rākṣasa. Thus He established in the great forest known as Madhuvana the town known as Mathurā.

SB 9.11.13-14, Translation:

Śatrughna had two sons, named Subāhu and Śrutasena. When Lord Bharata went to conquer all directions, He had to kill many millions of Gandharvas, who are generally pretenders. Taking all their wealth, He offered it to Lord Rāmacandra. Śatrughna also killed a Rākṣasa named Lavaṇa, who was the son of Madhu Rākṣasa. Thus He established in the great forest known as Madhuvana the town known as Mathurā.