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.

Used to indicate repetition in sign language glosses.

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

and

more

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