The pdf values are defined so that the total area under the pdf curve equals 1, but these values will exceed 1 (and, hence, not look like probabilities) when the range of X is less than one unit. To make pdf values look more like probabilities, you can adjust for that roughly like this:
% Generate some example values that look a little like yours:
mu = 0.25;
sigma = 0.1;
data = randn(500,1)*sigma + mu;
range = max(data) - min(data);
figure;
hold on;
nbins = 20; % for the histogram
histogram(data,nbins,'Normalization','probability','DisplayStyle','stairs');
pd = fitdist(data,'Kernel');
xValues = 0:0.001:0.5; % for computing the pdf
y = pdf(pd,xValues) / nbins * range; % adjust to match probability based on nbins & range
plot(xValues,y)
