What is the meaning of +?

Addition, additive operation.

Explicitly indicates that the next number is positive.

"Or more"; indicates that a number is the minimum quantity or amount.

From the positive side.

A disjoint union, a coproduct.

An inclusive disjunction.

A wild type.

A grafted hybrid.

A string concatenation in some programming languages (that might be ambiguous with an additive operation).

Detects one or more occurrences of the preceding element.

Check.

A placeholder standing for the international call prefix in phone numbers.

An affirmative result from a laboratory test.

An anode.

Indicating north.

Augmented.

Written by a bishop before his signature.

When placed between key names, indicates that they should be pressed simultaneously.

and

more

Abbreviation of and.

Abbreviation of and.

Used to connect two elements: and, plus.

denotes the immigration policy where the preceding number is the number of days required for quarantine and the following number is the number of days for medical monitoring

Source: wiktionary.org