Items and weight are tracked in terms of load. Each item the size of a human head or 5 lbs is considered 1 load. PCs are able to carry load equal to their STR score without issue.

Heavy armor is 5 load, light armor is 2 load. Items and weapons are 1 load each hand used when holding or wielding that item. Other miscellany can be stacked into 1 load.

Carrying load over your STR causes you to be encumbered, which reduces your speed by 5’ for every point of load over your STR score, and forces disadvantage on all checks.