There have been minor variations of this coin between 1879 and 1901, but the basic design remains essentially the same.
There are two major variations.
Some pieces have a seated woman on one side, and a wreath of leaves on the other side, with the value beneath the woman, and the date underneath the wreath.
Other coins have 'REPCA DE GUATEMALA' and a shield with 'DE-SEYBRE DE 1821' written inside on one side, and two ears of wheat along with the denomination on the other side. The date is found underneath the shield.
There are two minor variations of the seated woman coins. Some coins have a large wreath on the side with the date, and others have a small wreath. The values are essentially the same, except for the 1893 coins.
Your 1900 piece, H, is made of copper nickel and is therefore not worth very much, but prior pieces were made of silver and carry a little more value.
Here is what the catalogs say about the Guatemala half real in average circulated condition:
1878 to 1890: about $5 US dollars catalog value
1883 (3 over 1 overdate): $15
1883 (normal coin) $10
1893 with seated woman, small wreath: $30
1893 with seated woman, large wreath: $15
1893 without seated woman: $10
1894 to 1897: about $3
1899: about $2
1900 to 1901: less than $1, when well preserved about $1
These are catalog values. Be sure you understand what this means by reading our Important Terminology page.